The invention resides in a switching element, which is at least partially embedded in a casting compound and a method of applying the casting compound to the switching element for waterproofing the switching element, preferably the area of connection for electrical conductors.
The sealing of electrical switching elements by casting them into watertight casting compounds is generally known and in wide use. In such processes, not only the complete switching components are cast into a housing, but often only the electrical connections in the area of the connector pins are embedded in a casting compound. For this purpose, a casting containment is provided in the area of the connecting pins which is either integral or which can be attached and which is filled from the top in a well-known manner by a dispensing unit. During the filling procedure, a dispensing needle is so guided, that the filling process starting at the containment bottom proceeds as uniformly as possible toward the containment top edge. Single component or two-component materials may be used for that purpose preferably in the form of liquid resins which are hardened for example by being heated after they have been filled into the containment.
Such well known casting in a containment, which is open on top or at least partially open, has important disadvantages. In manual operations, the work result depends to a great degree on the skill of the person who guides the dispensing needle as it is important to fill the containment uniformly to prevent the formation of air bubbles. However, this disadvantage occurs not only during manual operation, but also with mechanically controlled dispensing units since a uniform filling procedure from the bottom to the top is impeded by wire connections or wires. During the filling of the upwardly open casting containments turbulence occurs even during carefully handled filling procedures whereby cavities and air bubbles may be generated so that the hardened cast may include cavities or bubbles, which may lead to leaks. Also, difficulties are encountered with the accurate dosing of the fill volume so that, with non-uniform filling, there may be in the containment and at the connecting cables excess material which must be removed, that is, scraped off by expensive additional procedures. As a result, the cast elements may not have an attractive appearance and may be unnecessarily expensive. Also, the timing for the casting procedure cannot be controlled in an optimal manner.
FIG. 1 shows a simple arrangement for the casting of microswitches as it is known in the art, wherein several switches 10 are arranged side-by-side in a support structure 12 with a casting containment 11 disposed on the switches 10. The wires of a wire harness 15 are already soldered to the connector pins 16. The dispensing or dosing unit 17 with the dispensing needle 18 is moved from casting containment 11 to casting containment in order to fill the containments with casting material through the top opening.
With the methods used so far a partially or fully automatic filling process could not be utilized because of the disadvantages mentioned earlier.
It is therefore the object of the present invention to provide a arrangement, whereby switching elements can be either partially or fully embodied in a casting resin in a housing or a casting containment wherein the housing or containment parts are so formed that the process can be performed fully automatically, while essentially no air enclosure or air bubbles can develop during the casting procedure.